Re: kern/43240 (KASSERT umap->refcount != 0 failed (sys/uvm/uvm_bio.c:248))

[Nicolas Joly <njoly%pasteur.fr@localhost>]

On Sun, Mar 18, 2012 at 02:08:04AM +0000, chs%NetBSD.org@localhost wrote:
> Synopsis: KASSERT umap->refcount != 0 failed (sys/uvm/uvm_bio.c:248)
> 
> Responsible-Changed-From-To: kern-bug-people->chs
> Responsible-Changed-By: chs%NetBSD.org@localhost
> Responsible-Changed-When: Sun, 18 Mar 2012 02:08:02 +0000
> Responsible-Changed-Why:
> I'm looking at this.
> 
> 
> State-Changed-From-To: open->feedback
> State-Changed-By: chs%NetBSD.org@localhost
> State-Changed-When: Sun, 18 Mar 2012 02:08:02 +0000
> State-Changed-Why:
> I tried this to a netbsd/amd64 box running 6.0_BETA but it didn't crash:
> 
> $ cat /dev/zero | rsh nbsd-amd64 dd of=/dev/null bs=2g
> dd: stdin: Bad address
> 0+0 records in
> 0+0 records out
> 0 bytes transferred in 0.021 secs (0 bytes/sec)
> $
> 
> does it still crash for you?

I cant test on the original machine anymore (it has gone under
production running Linux with only 48GB ram). So itried to reproduce
it on a smaller and64 machine with only 8GB ram ...

I can't make it crash, as i can't make any network trafic ;)

njoly@lanfeust [~]> cat /dev/zero | rsh localhost dd of=/dev/null bs=2g
dd: stdin: Bad address
0+0 records in
0+0 records out
0 bytes transferred in 114.770 secs (0 bytes/sec)

It doesn't return as fast as your test, the dd process cannot be
killed during that time (even with kill -9), it eats memory and may
make the system unresponsive.

I then checked a few other bs values for the same command line. No
problem with 1024m, 1536m, 2047m ... all other upper values fails. So
there's still something weird with bs >= 2g when piping to rsh. Just
for the record, every value i tested again worked just fine without
rsh after pipe (= locally).

But no crash.

-- 
Nicolas Joly

Projects and Developments in Bioinformatics
Institut Pasteur, Paris.